GAS LIGHT FROM COAL. $7 



Reference to Mr. S. Clegg's improved Apparatus for extract- 

 ing Carburetted Hidrogen Gas from Pit Coal. See Plate 

 III, figs. 1, 2, 3, 4, 5, and u\ 



In fig. 1, A shows the cast iron retort, into which are put Description of 

 the coals intended to be decomposed by means of a fire the apparatus, 

 underneath it, the heat of which surrounds every part of it, 

 excepting the mouth or part by which the coals are intro- 

 duced. The lid or iron plate B, which covers the mouth 

 of the retort, is ground on air tight, and fastened by means 

 of a screw in the centre; C is a shield or saddle of cast 

 iron, to preserve the retort from being injured by the inten- 

 sity of the fire underneath it, and to cause it to be heated 

 more uniformly. D D D represents the cast iron pipe which 

 conveys all the volatile products of the coal to the refrige- 

 ratory of cast iron JE, in which the tar, &c, extracted from 

 the coal is deposited, and whence they can be pumped out 

 by means of the copper pipe 1\ G is the pipe which con- 

 veys the gas to the top of the cylindrical vessel or receiver 

 //; this receiver is air tight at the top, and consequently 

 the gas displaces the water in the vessel //, to a level with 

 the small holes, where the gas is suffered to escape and rise 

 through the water of the well /, into the large gasometer 

 K, The use of the vessel // is pointed out as follows, viz. 

 If the pipe G reached all through the water, without pass- 

 ing into the vessel H 9 the gas would not be rendered pure 

 or washed; and if part of the pipe did not rise above the 

 water, the water would have free communication with the 

 tar, besides exposing the retort A to a very great pressure, 

 so. as to endanger its bursting when red hot. This vessel or 

 receiver II, in a large apparatus, is about eighteen inches 

 diameter, and two feet long ; the quantity of gas, therefore, 

 which it contains, is sufficient to fill the pipes and retort 

 when cool, prevent the pipe G from acting as a siphon, and 

 expose the gas to the water without endangering the re- 

 tort. 



When the operation begins, the upper part of the cylin- 

 drical gasometer K, fig. I, made of wrought iron plates, is 

 sunk down nearly to a level with the top of the circular well 

 J, and is consequently nearly filled with water, but it rises 



gradually 



